Image guided surgical interventions to treat cardiac defects offer the promise of minimizing the invasiveness of the procedure, avoiding open heart surgery and cardiopulmonary bypass, and reducing recovery time. Beyond these advances, they also offer the promise of providing real-time physiologic information on structure and function of the heart during the repair, potentially improving outcome in reconstructive operations. To realize these objectives however, a number of advances are required in imaging technology, procedure development, and instrument design. In our current BRP we have focused on developing imaging, image processing and display techniques, and devices to perform beating heart repair in relatively static structures such as atrial septal defects. We have succeeded in performing beating heart repair in a wide variety of atrial septal defects and have developed the technology (imaging, navigation aids, and devices) to a level where phase I clinical trials are now being developed. In this proposal we plan to further develop technology and devices to repair defects that involve highly mobile and difficult to image structures. We will use three common procedures: Tissue ablation for atrial fibrillation, closure of ventricular septal defect, and repair of prolapsed mitral leaflet as our platform procedures to develop the technology. These procedures represent common operations performed to repair congenital and acquired heart defects and, relevant to this proposal, they represent a current and significant technical challenge for beating heart intervention. In Aim 1 we will : Develop high spatial and temporal resolution ultrasound imaging;in Aim 2 we will: Develop high spatial and temporal resolution imaging-based tracking methods and displays for tissue and instruments;and in Aim 3 we will: Design devices, and dexterous, high-speed, actuated delivery instruments for grasping and attaching to highly mobile and delicate intracardiac structures. We will maintain the multidisciplinary team of investigators that has collaborated closely in the current BRP grant to now address the more challenging problem of working in the beating heart with structures that are moving rapidly, and defects that require complex navigation and high resolution imaging. Development of these tools and technology will enable catheter and beating heart surgery-based reconstructive operations to repair a wide range of intracardiac defects. PUBLIC HEALTH RELEVANCE Image guided beating heart repair of heart defects offers the promise of avoiding complex and risky open heart operations. We have developed techniques for performing repair of simple defects using 3-Dimensional ultrasound for imaging, image processing to provide instrument navigational aids inside the heart, and specialized surgical tools. We now propose to extend our work to address repair of complex heart lesions that require higher image resolution and specialized instruments to compensate for cardiac motion.